In recent years, mainly because of the energy crisis, salt water solar ponds have been developed for utilization as alternative energy sources. Conventionally, salt water solar ponds comprise an upper wind-mixed layer, a lower convective heat storage layer and an insulating salt-gradient halocline interposed between the upper wind-mixed layer and lower heat storage layer. Solar radiation incident on the solar pond penetrates the upper and halocline layers reaching the lower layer where it is stored, due to the presence of the insulating halocline. The stored radiation available in the form of heat at temperatures up to 100.degree. C. or more provides an energy source suitable for heating purposes or generating electrical power.
In order to produce power from salt water solar ponds, it is necessary to extract heat from the storage layer. In addition, the heat engine used to produce power conventionally contains a condenser which needs to be cooled. U.S. Pat. No. 3,372,691 discloses a system for converting bodies of water into efficient solar collectors or solar ponds which can be used for power production. In order to use this technique to produce power, pumps which consume energy, are required for extracting hot brine from the heat storage layer and sea water supplied from the sea is needed to cool the condenser of a heat engine in an indirect heat exchanger.
In U.S. Pat. No. 4.377.071 a solar energy power station is disclosed wherein the heat storage layer of a solar pond and the wind-mixed layer of the pond respectively form the heat source and heat sink of the power station. The power plant includes a boiler, responsive to water from the heat storage layer, for vaporizing a working fluid, a prime mover for producing work by extracting heat from vaporized working fluid and a condenser cooled by water from a cooling pond connected to the solar pond such that only water in the wind-mixed layer is exchanged with water from the cooling pond. Once again, pumps which consume electrical power supply hot brine from the heat storage layer to the boiler, while the condenser used in the system is an indirect heat exchanger. Both these factors reduce the overall efficiency of this power station.
It is therefore an object of this invention to provide a new and improved method of and apparatus for producing electrical power from a salt water solar pond wherein the disadvantages of the prior art, as outlined above, particularly in relating to overall efficiency, are reduced or substantially overcome.